In this talk I will describe the densest predicted
state of matter—color-superconducting quark matter.
A color superconductor is very different from an “ordinary”
electrical superconductor. It occurs at ultra-high density
and has a much richer phase structure
because quarks come in many varieties.
Quark matter may well exist in the core of neutron
stars, and the search for signatures of its presence is
currently proceeding.
I will give an accessible review of the features of
color-superconducting quark matter,
and discuss some ideas for finding it in nature.